Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities:
Net Income	$ 58,734,000	$ 56,036,000	$ 45,527,000
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Provision for Credit Losses	4,500,000	200,000	5,533,000
Depreciation and Amortization	2,769,000	2,756,000	2,421,000
(Benefit) Provision for Deferred Income Taxes	(1,962,000)	(3,254,000)	5,462,000
Net Amortization of Investment Security Premiums & Discounts	1,159,000	510,000	861,000
Amortization of Core Deposit Intangible	626,000	639,000	228,000
Accretion of Discount on Acquired Loans	(166,000)	(47,000)	(153,000)
Net (Gain) Loss on Sale of Investment Securities	(40,000)	(1,000)	1,260,000
Net Loss (Gain) on Sale of Property & Equipment	(32,000)	87,000	(273,000)
Earnings from Equity Investment	0	0	(66,000)
Dividends from Equity Investment	0	0	63,000
Gain on Remeasurement of Previously Held Equity Investment	0	0	(997,000)
Net Change in Operating Assets & Liabilities:
Net (Increase) Decrease in Interest Receivable and Other Assets	(3,333,000)	18,949,000	(2,098,000)
Net (Decrease) Increase in Interest Payable and Other Liabilities	(4,136,000)	4,983,000	6,000
Net Cash Provided by Operating Activities	58,119,000	80,858,000	57,774,000
Investing Activities:
Purchase of Investment Securities Available-for-Sale	(670,550,000)	(652,280,000)	(465,414,000)
Proceeds from Sold, Matured, or Called Securities Available-for-Sale	383,257,000	644,244,000	550,727,000
Purchase of Investment Securities Held-to-Maturity	(22,020,000)	(16,376,000)	(9,813,000)
Proceeds from Matured, or Called Securities Held-to-Maturity	13,299,000	10,871,000	10,647,000
Net Loans & Leases Paid, Originated or Acquired	(427,573,000)	(102,413,000)	(276,066,000)
Principal Collected on Loans & Leases Previously Charged Off	524,000	220,000	158,000
Cash Paid for Acquisition, Net	0	0	(5,987,000)
Additions to Premises and Equipment, Net	(7,709,000)	(15,537,000)	(4,577,000)
Purchase of Other Investments	(6,063,000)	(4,400,000)	(5,750,000)
Proceeds from Sale of Property & Equipment	81,000	41,000	986,000
Net Cash Used in Investing Activities	(736,754,000)	(135,630,000)	(205,089,000)
Financing Activities:
Net Increase in Deposits	782,248,000	215,187,000	148,033,000
Stock Repurchases	(2,834,000)	0	(31,152,000)
Cash Dividends	(11,700,000)	(11,221,000)	(11,151,000)
Net Cash Provided by Financing Activities	767,714,000	203,966,000	105,730,000
Net Change in Cash and Cash Equivalents	89,079,000	149,194,000	(41,585,000)
Cash and Cash Equivalents at Beginning of Year	294,758,000	145,564,000	187,149,000
Cash and Cash Equivalents at End of Year	383,837,000	294,758,000	145,564,000
Supplementary Data
Cash Payments Made for Income Taxes	9,581,000	7,342,000	7,971,000
Issuance of Common Stock to the Bank's Non-Qualified Retirement Plans	403,000	6,973,000	10,502,000
Interest Paid	10,903,000	11,755,000	7,731,000
Supplementary Noncash Disclosure
Lease Liabilities Arising from Obtaining Right-of-Use Assets	0	5,645,000	0
Acquisitions:
Fair Value of Assets Acquired	0	0	234,456,000
Fair Value of Liabilities Acquired	$ 0	$ 0	$ 192,809,000